In subsea production, electrically operated apparatuses below sea level are typically supplied by power from sea- or land-based host facilities. Operating power, in this connection typically at voltages of 1 kV and above, is conducted via cable conductors to submerged process control equipment, pumps and compressors, transformers, motors, and other electrically operated equipment, and is introduced to encapsulated power consumers by means of a cable termination and connector, in this specification referred to as a high voltage electrical penetrator.
An electrical penetrator for subsea purpose is previously known from WO 2007/096760 A1. This known electrical penetrator accommodates cable termination components by which a cable conductor is electrically connected to a conductor pin that is accessible from a connector end of the electrical penetrator. The conductor pin is fixedly embedded by moulding into a synthetic resin insulator body, which is seated in a penetrator housing and is sealed against the penetrator housing by means of O-rings, or other types of seals.
In submerged applications it is for several reasons indispensable that the electrical penetrator is protected from the ingress of water. Considerable pressures prevailing at operational water depths down to and below 1,000 m, e.g., requires a penetrator structure that is adapted to existing ambient pressures and differential pressures over seals, the bushing and other structures included in the electrical penetrator.
Differential pressures applied to the electrical penetrator from surrounding sea and from a pressurized device enclosure thus strive to displace the bushing relative to the penetrator housing. In the cited known electrical penetrator, pressure induced displacement of the bushing is prevented through a slanting radial shoulder on the exterior of the insulator body receiving abutting support from a corresponding inner shoulder on the penetrator housing. At higher pressures, the angular transitions into the slanting surfaces on the insulator body and on the penetrator housing respectively however induces local tensile and shear stresses in the insulator body material, and sets a limit for allowable nominal and differential pressures over the bushing. In practise, the cited previously known electrical penetrators having synthetic material insulator bodies are for security reasons qualified for operation at pressures of 200 bars in one direction and 100 bars in the opposite direction. Other penetrator designs having ceramic or glass insulator bodies may be structured to withstand higher pressures, but suffer from a more complex production and associated higher production costs.
An electrical penetrator for subsea application is previously known from RU 2050651 C1. A bulbous portion of a conductor element is embedded in elastomeric polymer material which is injection moulded into a cavity that is formed between the conductor element and a spherical seat of a penetrator housing which surrounds the conductor element. Albeit the structure of the device disclosed in RU 2050651 C1 is readable on the preamble of claim 1 of the present invention, it is acknowledged that the device disclosed in RU 2050651 C1 is however less suitable for the purpose of conducting electric current at high voltages where high differential pressures are prevailing, due to the limited yield strength of an elastomeric material and due to the limited thickness of the injection moulded polymer insulation which is available through the dimension of the gap that is formed between the conductor element and its seat.